Recommended Gear Oil

I am going to service the rear diff. Putting on an '08 cover on but wanted to see what everyone suggests for rear diff gear oil.. I see Ford specs call for 75W-90 synthetic (3.8 qts) and 8 ounces of Friction Modifier. I was considering Royal Purple and saw on thier website it comes with friction modifier in it already.. Anyone running Royal Purple or suggest something else?

Get the royal purple you wont regret it.

im runnin royal purple 75w-140 i think yeah its good. i didnt have to add any modifier or anything. plus its supposed to be pretty good stuff

I run Redline synthetic. You can get it with or without the modifier already added.

I am going to service the rear diff. Putting on an '08 cover on but wanted to see what everyone suggests for rear diff gear oil.. I see Ford specs call for 75W-90 synthetic (3.8 qts) and 8 ounces of Friction Modifier. I was considering Royal Purple and saw on thier website it comes with friction modifier in it already.. Anyone running Royal Purple or suggest something else?

recheck your manual i'm pretty sure you want 75w-140-10.50" 6.9pints
75w-90 is for the front diff. Dana 50 -3.8 pints Dana 60 5.8 pints

i running mobil 1

I'll be running redline.

recheck your manual i'm pretty sure you want 75w-140-10.50" 6.9pints
75w-90 is for the front diff. Dana 50 -3.8 pints Dana 60 5.8 pints

I double checked with Alldata and you are correct, 75W-140 rear 7.0 pints..

Front is 75W-90

Thanks!

recheck your manual i'm pretty sure you want 75w-140-10.50" 6.9pints
75w-90 is for the front diff. Dana 50 -3.8 pints Dana 60 5.8 pints

Ya I was gonna say, the rear is 75-140

Im running Royal purple..........

Ya I was gonna say, the rear is 75-140

Im running Royal purple..........

Ok sounds good, did you have to add friction modifier?

I just put in 75w-140 Lucas.

I am using Schaeffer's 75W-140 gear oil - no friction modifier needed.

http://www.schaefferoil.com/datapdf/167.pdf

Compare the technical data sheets

Ok sounds good, did you have to add friction modifier?

No the Royal Purple synthetic already has it

does royal purple , or any one else make the weight for the front?
I saw one user using the same both f&back.. another guy said it should be diff ...any ideas..or comments.

does royal purple , or any one else make the weight for the front?
I saw one user using the same both f&back.. another guy said it should be diff ...any ideas..or comments.

Yes, I have both here in Royal Purple.. Specs call for 75W-90 front and rear is 75W-140..

This is my little weekend project along with the T-case.

Schaeffers 75-90 267 in both front and rear. No modifier.

The friction modifier is for nosie anyways right?

no. have u ever turned with posi trac. sounds like ur doin a burnout.

For an over the counter synthetic gear oil you CANNOT beat RedLine. The only way to get a better oil is to have it custom blended. Thicker is always better for gears, use at least a 140wt or higher for the rear diff, esp. if you tow.

I prefer to get the oil without any friction modifier in it. Then add a LITTLE at a time until the chatter stops. The FM additives make the clutches slip to quiet them down, so you don't want to put in more than you have to.

Yes, I have both here in Royal Purple.. Specs call for 75W-90 front and rear is 75W-140..

This is my little weekend project along with the T-case.

Use royal purple syncromax in the t-case mine likes it.

Ok I'll give it a try!

i am considering changing over to Schaeffers all around. I will be switching to their motor oil, and possible doing my diffs with it. I have not heard a bad thing about their products and everyone who uses it, swears by it. Just gotta order it up.

Went with the Royal Purple and threw on a new finned aluminum read diff cover that come on the '08 superdoodies.. They are only $40 too and are a direct fit!

(its a little dirty under there because it has been raining hard all day)

http://powerstrokenation.com/photopost/data/500/medium/diff.jpg

Deputydog...what's the story behind the spare tire?

Diezel Dawg, I just ordered a case of Schaeffer 9000 5w-40 from JTHarvey. I'll be changing motor oil as soon as it gets here. I also plan to switch all of the other fluids over to Schaeffer too. It's not cheap but it's significantly cheaper then the purple stuff or Redline. I got a 6 pk. of oil analysis kits and don't plan on changing it till the OA says too. Oh yeah, I'll be installing a bypass filter at the same time.

Deputydog...what's the story behind the spare tire?

Diezel Dawg, I just ordered a case of Schaeffer 9000 5w-40 from JTHarvey. I'll be changing motor oil as soon as it gets here. I also plan to switch all of the other fluids over to Schaeffer too. It's not cheap but it's significantly cheaper then the purple stuff or Redline. I got a 6 pk. of oil analysis kits and don't plan on changing it till the OA says too. Oh yeah, I'll be installing a bypass filter at the same time.

Well when I got my truck about 4 yrs ago, the spare was missing. I went to the salvage yard and got this one to throw under it.. Dunno what that means. The writting is upside down, it really says "SSV MON".. :shrug:

Deputydog...what's the story behind the spare tire?

Diezel Dawg, I just ordered a case of Schaeffer 9000 5w-40 from JTHarvey. I'll be changing motor oil as soon as it gets here. I also plan to switch all of the other fluids over to Schaeffer too. It's not cheap but it's significantly cheaper then the purple stuff or Redline. I got a 6 pk. of oil analysis kits and don't plan on changing it till the OA says too. Oh yeah, I'll be installing a bypass filter at the same time.


Cool, Deputy dog and i are going to order a few cases of it to get the free shipping. i am anxious to see how my truck reacts to it. should be really nice for it during the winter